How to Overwinter Bonsai: Timing and Precautions

Last time, we introduced where to place your bonsai for winter storage.
In this journal, we'll discuss the timing and precautions for overwintering.

First, timing.
When daytime temperatures stay below 5°C for about a week, it's time to prepare your bonsai for winter.
If you're unsure of the timing, using frost as a guide is one approach.
If frost forms on your bonsai, that's a good sign it's time for winter preparation.
Preparing too early isn't good for your bonsai either, so check temperatures and frost regularly to ensure you're fully prepared for winter.

Next, important points to note.
・Cleaning and pest control
During winter storage, cleaning and pest control are essential.
The base of the trunk is particularly prone to dirt buildup, so clean it thoroughly.
The winter shelter is warm and comfortable for bonsai, but this also creates an environment where pests can easily thrive.
Clean frequently to maintain a clean environment.
Even if no visible changes are apparent, take preventive measures about once a month using insecticide or plant-safe insect repellent spray.

・Exposing bonsai to cold weather
When overwintering bonsai, it's not only about protecting them from the cold but also allowing them to experience it.
Avoid immediately moving them into a winter shelter or indoors just because it's gotten cold.
Bonsai that never encounter cold air and fail to sense winter's arrival tend to develop imbalanced growth.
They may grow abnormally and produce new shoots.
Shoots emerging in winter are vulnerable to cold and struggle to develop properly.
To cultivate healthy bonsai, it is essential to allow them to experience winter's chill.

That concludes our discussion on the timing and precautions for overwintering bonsai.
Winter is just around the corner.
Let's take thorough overwintering measures so we can nurture our bonsai healthily into the next spring!

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